Silver (Ag<sup>+</sup>) doped phosphate glass exhibits an intense photoluminescence (PL) when the non-irradiated Ag<sup>+</sup>-doped
phosphate glass is excited with about 230 nm ultra-violet light. In x-ray irradiated glass, intense
radiophotoluminescense (RPL) is observed when the irradiated glass is excited with about 340 nm ultra-violet light. It
is found that the RPL spectrum includes two emission bands such as blue emission band peaked at about 460 nm
(lifetime: about 6.6 ns) and yellow RPL emission band peaked at about 560 nm (lifetime : about 2.2μs). The PL
intensity is decreased with increasing x-ray irradiation dose, while the RPL intensity is increased with x-ray absorbed
dose. For the annealing of x-ray irradiated glass at 523 K, the RPL intensity is decreased with annealing, while the PL
intensity is increased with annealing. The RPL is vanished and the PL is recovered at original intensity by annealing at
523 K for 40 min. This means that there is a complementary relationship between the PL and RPL on irradiation and
heat-treatment processes. The RPL intensity is increased with increasing the x-ray absorbed dose in the range from
0.01 mGy to about 20 Gy, showing that the Ag<sup>+</sup>-doped phosphate glass can be useful for individual radiation monitoring
and environmental radiation monitoring. On the basis of such potentiality of glass as the dosimeter, the application of
Ag<sup>+</sup>-doped phosphate glass on environmental radiation monitoring is discussed and the RPL response of the glass for α-
particle and heavy-particle (He, C, Fe particle) irradiation is demonstrated.

CsBr phosphor ceramics doped with different luminescence center such as In<sub>2</sub>O<sub>3</sub>, Eu<sub>2</sub>O<sub>3</sub>, EuCl<sub>3</sub>, SmCl<sub>3</sub>, TbCl<sub>3</sub>, GdCl<sub>3</sub> or NdCl<sub>3</sub> as a candidate of a new photosimulable phosphor for medical x-ray imaging sensor are prepared using a conventional ceramic fabrication process. It is found that x-ray-irradiated Eu-doped CsBr (CsBr:Eu) exhibits intense photostimulated luminescence (PSL). The peak wavelength of the PSL emission and stimulation spectra of CsBr:Eu phosphor ceramic sample is 450 nm and 690 nm, respectively. The dependence of PSL properties on preparing conditions of phosphor ceramic samples, such as Eu concentration, sintering temperature and sintering time, is studied and the optimum preparing condition is also studied. It is found that the PSL intensity of CsBr:Eu phosphor ceramics fabricated under optimum preparation condition is higher than that of commercially available imaging plate (IP) using BafBr:Eu. The image quality of the IP using CsBr:Eu phosphor film is better than that of commercially available IP.

Odor sensor based on the surface plasmon resonance (SPR) is studied for detection of harmful gases such as ammonia and amine gases. The sensor was prepared by depositing the molecular recognition membrane on substrate coated with Au thin film using plasma chemical vapor deposition (CVD) method. It is found that the SPR sensor with acrylic acid membrane exhibited an excellent selectivity and high sensitivity for ammonia and amine gases.

In order to develop the sensor system for environmental monitoring, chemical sensors using quartz crystal microbalance (QCM) coated with acrylate-film with different functional groups, and styrene-film as a molecular recognition membrane are prepared using plasma-polymerized chemical vapor deposition (CVD) method. It is found that the sensor response for various gases strongly depends on the functional group of molecular recognition membrane of the sensor. The styrene-film coated sensor exhibits no selectivity for specific gas and responds to various gases. It is also found that the styrene-film coated sensor in conjunction with principal component analysis is useful for identification of gas kinds in environmental monitoring.

It is demonstrated that the commercially-available imaging plate (IP) using BaFBr:Eu photostimulable phosphor is useful as a phosphore material for 2D UV image sensor though the sensitivity of the IP for UV-ray is not so high. The new phosphore materials as alternative materials for the IP are surveyed for many possible phosphore materials and consequently we find out that the Ca<SUB>x</SUB>Sr<SUB>1-x</SUB>S:Eu,Sm phosphore ceramics exhibited a high photo stimulated luminescence (PSL) intensity for UV-ray irradiation. It is found that the SrS:Eu,Sm phosphore ceramics exhibits good PSL characteristics for UV-ray imaging and the PSL characteristics are depended on the content of CaS and the concentration of Eu and Sm doped.

The functional design of the smart electronic nose using polymer-film coated quartz resonator gas sensors, based on the solubility parameter of sensing membrane and gases, is carried out in order to develop the sensor with excellent selectivity and high sensitivity for harmful gases such as toluene, acetaldehyde and ammonia gases. The polymer-films such as propylene-butyl, poly-carbonate and acrylic-resin of which the solubility parameter almost coincide with that of toluene, acetaldehyde and ammonia gases, respectively, are chosen as a sensing membrane material coated on the quartz resonator. It is found that propylene-butyl-film coated quartz resonator gas senor exhibits a high sensitivity and an excellent selectivity for toluene and p-xylene gas, as it is expected from the functional design based on the solubility parameter. It is also found that poly-carbonate- film coated sensor and acrylic-resin-film coated sensor exhibit high sensitivity and excellent selectivity for acetaldehyde and ammonia, respectively, as it is also expected. The results strongly suggest that the solubility parameter is effective to functional design of the sensing membrane of quartz resonator gas sensors. The identification of gas kind is successfully possible by the principal component pattern recognition analysis of the transient response of the each sensor for gases.

The Boolean logic operations such as OR, AND and NOR are demonstrated using photostimulated luminescence (PSL) phenomenon in the imaging plate (IP) which is made by BaFBr:Eu photostimulable phosphor. The PSL in Eu and Sm co-doped SrS (SrS:Eu,Sm) phosphor ceramics is studied in order to develop a smart erasable and rewritable optical memory utilizing PSL phenomenon, because the SrS:Eu,Sm phosphor ceramics which are excited with UV-light or visible light exhibits an intense PSL, compared with that in UV-irradiated IP. Intense PSL with a peak at about 600 nm is observed in SrS:Eu,Sm phosphor ceramics which is stimulated with infrared light after irradiation with ultraviolet-(UV) light or visible-light. The PSL characteristics of SrS:Eu,Sm phosphor ceramics as a photostimulable material for the optical memory are reported.

The copolymerized propylene-butyl of which the 'solubility parameter' almost coincides with that of hydrocarbon and organic solvent gases such as toluene, xylene, diethyether, chloroform and acetone, is chosen as a material of the sensing membrane coated on the quartz resonator. It is found that copolymerized propylene-butyl-film coated quartz resonator microbalance gas sensor exhibits high sensitivity and excellent selectivity for these gases, especially for toluene and xylene gas, suggesting that the 'solubility parameter' is effective to functional design of the sensing membrane of quartz resonator gas sensors.

We found that an intense yellow photostimulated luminescence (PSL) can be observed when UV-light or visible-light irradiated SrS:Eu,Sm and CaS:Eu,Sm phosphor ceramics are estimated with IR light with wavelength from 800 nm to 1700 nm. This phenomenon in these phosphor materials is applicable to a novel 2D IR sensor. In the paper, we describe PSL characteristics in SrS:Eu,Sm and CaS:Eu,Sm phosphor ceramics, especially in SrS:Eu,Sm phosphor ceramics, and discuss the mechanism of the PSL which is observed by stimulating the phosphor with IR light.

The photostimulated luminescence (PSL) characteristics of alkali halide phosphors, such as KCl:Eu, KBr:Eu and KCl<SUB>x</SUB>Br<SUB>1-x</SUB>:Eu phosphors, as new storage photostimulable phosphor materials for the imaging plate in computer radiography are investigated. Intense 420 nm PSL is observed in X-ray-irradiated KCl<SUB>x</SUB>Br<SUB>1-x</SUB>:Eu phosphor. The PSL intensity increases linearly with increasing X-ray irradiation dose over the wide range, showing a good storage material for the imaging plate in computed radiography. The KBr:Eu phosphor exhibits excellent fading characteristics, which showing that the KBr:Eu phosphor is useful as a material for medical imaging utilizing PSL phenomenon. The mechanism of the fading is also discussed.

The sensitivity of the chemical sensor, based on the resistance change of Al<SUB>2</SUB>O<SUB>3</SUB>-doped and SnO<SUB>2</SUB>-doped ZnO (ZnO:Al and ZnO:SnO<SUB>2</SUB>) thin film, is studied for exposure to various gases. It is found that the ZnO:Al and ZnO:Sn thin film chemical sensor has a high sensitivity and excellent selectivity for amine (TMA and DMA) gas and ethanol gas, respectively. The ZnO:Al (5.0 wt%) thin film chemical sensor which exhibit a high sensitivity for exposure to odors from rotten sea foods, such as salmon, sea bream, oyster, squid and sardine, responds to the freshness change of these sea foods. The ZnO:SnO<SUB>2</SUB> (78 wt%) thin film chemical sensor which exhibit a high sensitivity for exposure to aroma from alcohols, such as wine, Japanese sake, and whisky, responds to the freshness change of these alcohols.

Photostimulated luminescence (PSL) in Eu and Sm co-doped II-VI compound phosphor ceramics such as SrS and CaS is studied in order to develop a smart erasable and rewritable optical memory utilizing PSL phenomenon. Intense PSL with a peak at about 600 nm and 650 nm is observed, respectively, in SrS:Eu,Sm and CaS:Eu,Sm posphor ceramics which are stimulated with infrared light after irradiation with ultraviolet-(UV) light or visible-light. The PSL characteristics of SrS:Eu,Sm posphor ceramics for the optical memory are reported. The OR Boolean logic operation is demonstrated using the PSL phenomenon in photostimulable phosphor materials.

New organic-inorganic fluorescent thin gel films included with laser dyes or fluorescent organic pigments have been prepared for display application. The florescent dyes (benzoxazolium, pyrromethene, and rhodamine dyes) and super-fine particles of fluorescent pigments (coumarin and perylene) were successfully incorporated into thin silicate gel films prepared from tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), and methoxysilane oligomer (MTSO) under acid catalyzed hydrolysis. The blue, green, and red luminescence were observed from these thin films (thickness: 100 - 400 nm), respectively. Fluorescence spectra, fluorescent quantum yield and lifetime of thin gel films are examined. Fluorescent peaks for most of dyes and pigments used in gel films were similar to those in solution, and fluorescent lifetime for dyes and pigments used in gel films were 2.9 - 4.5 ns. Photostability of fluorescent gel films is dependent on fluorescent organic dyes and pigments used and/or silicate gel matrixes. Coumarin and perylene pigments have higher fluorescent quantum yield in gel film prepared from MTSO. The large Stokes shift was observed in fluorescent gel film using coumarin and benzoxazolium dyes. The coumarin and perylene pigments are significantly photo- stable in gel film prepared from MTSO, and photodegradation of perylene red after irradiation of 500 W Xi-lamp for 30 min is below 20%.

An efficient photostimulated luminescence (PSL) with a peak at about 420 nm is observed by stimulating ultra-violet (UV)-ray-irradiated europium-doped potassium chloride (KCl:Eu) crystalline phosphor with 560 - 580 nm light. The excitation and emission mechanism for the 420 nm PSL in UV-ray irradiated KCl:Eu phosphors are proposed. It is found that the PSL intensity increased with increasing irradiation dose of UV-ray, which indicating that the KCl:Eu is one of the most attractive candidates for two-dimensional UV-ray imaging sensor utilizing PSL phenomenon.

Intense optically stimulated luminescence (OSL) with a peak at about 420 nm is observed in ultraviolet (UV)-ray or x-ray irradiated europium-doped potassium chloride (KCl:Eu) crystals. The OSL intensity is increased with increasing UV-ray or x-ray irradiation dose. This suggests that KCl:Eu crystal is useful as a material for two-dimensional UV-ray or x-ray imaging sensor utilizing OSL phenomenon. The results obtained are consistent with the proposed emission mechanisms of the 420 nm OSL peak, based on the recombination of electrons released from the F centers with Eu<SUP>3</SUP> ions. The excitation mechanism for the OSL in UV-ray irradiated KCl:Eu crystals is also discussed.

Intense photostimulated luminescence (PSL) is observed, for the first time, in x-ray irradiated europium-doped potassium chloride (KCL:Eu) single crystals. The intensity of PSL with a peak at about 420 nm, which is emitted by stimulation with 560 nm light, is proportional to the optical density of the F centers, which are created by x-ray irradiation, over the wide range of the x-ray absorbed dose. This suggests that KCl:Eu is one of the most attractive candidates for a two-dimensional x-ray imaging sensor utilizing the PSL phenomenon.

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